Propellant composition containing a nickle-silver composite

ABSTRACT

Solid propellants compositions and method for the preparation thereof, comprising the addition of a staple to a wetted propellant composition, casting, subjecting the casting to a magnetic force in order to radially orient the staples therein, solidifying and recovering the product.

United States Patent 1191 Baumann et al.

1 PROPELLANT COMPOSITION CONTAINING A NICKLE-SILVER COMPOSITE Inventors: Robert P. Baumann, Dover; Eugene F. Bozza, Rockaway, both of N.J.; Gardner S. Hunt, Freeport, Maine The United States of America as represented by the Secretary of the Army, Washington, DC.

Filed: June 30, 1972 Appl. N0.: 267,737

Related U.S. Application Data Division of Ser. No. 120,683, March 3, 1971,

abandoned.

[7 3] Assignee:

521 U.S. c1 149/2, 149/20, 149/38,

149/44, 149/114 1111. c1 C06b 19/00 Field of Search 149/2, 3120, 114,

ing the product.

Jan. 8, 1974 ""iieferii'cifd UNITED STATES PATENTS 11/1965 Papell 149/87 X 8/1971 Sayles 264/3 R X 11/1971 Lenoir 264/3 C Primary Examiner-Stephen J. Lechert, Jr. 4 ttomey- Edward T. Kelley and Herbert Berl [5 7] ABSTRACT 4 Claims, 8 Drawing Figures INVENTORS lllll HH Hiul OMOTOR FlRlNGS "BASE COMPOSITON o MOTOR FIRINGS COMPOSITION |.O

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BURNING RATE PERFORMANCE FF'ENTEUJAW 8 i974 N N AMM iv m A BB \U P R E U RNN in 0. mm: 0 G Y B ATTORNEYS PROPELLANT COMPOSITION CONTAINING A NICKLE-SILVER COMPOSITE This is a division, of application Ser. No. 120,683, filed Mar. 3, 1971 now abandoned.

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a solid propellant composition having improved performance characteristics.

The present method comprises the steps of mixing conventional propellants ingredients to form a batch, adding a staple to the batch, agitating the mixture to obtain substantially even distribution of the staple throughout said mixture, casting the mixture, subjecting the casting to a magnetic force in order to magnetically orientate the staples within the castings, and solidifying the casting.

An exemplary propellant of the present invention may be composed of, a combination of; a binder, oxidizer, fuel and additives. The binder may be an inert or explosive polymer. Suitable binders include the following, singly or in combination: nitrocellulose; crosslinked nitrocellulose and plasticizer; polysulfide rubber; polyurethane; nitropolyurethane; petrin acrylate; polybutadiene acrylic acid copolymers; etc. Oxidizers include the following, singly or in combination: ammonium perchlorate; nitrionium perchlorate; potassium perchlorate; ammonium nitrate; cyclotetramethylenetetranitramine (HMX); cyclotrimethylenetrinitramine (RDX); pentaerythritol-tetrianitrate (PETN); etc. Fuels include the following, singly or in combination: aluminum; magnesium; aluminum and magnesium alloys; beryllium and beryllium alloys; hydrides of aluminum, magnesium or beryllium; boron and boron hydrides; etc. Additives may be utilized for the purpose of improving performance, stabilization and processability. Suitable additives include the following, singly or in combination: diphenylamine; 2-nitrodiphenylamine; N-methylparanitroaniline; magnesium oxide; resorcinol; phloroglucinol; lead oxide; lead salicylate; lead chromate; copper chromate; copper chromite; ferricacetylacetonate; prussian blue; etc. Plasticizers include the following, singly or in combination: nitroglycerin; butane-trioltrinitrate; triethyleneglycol dinitrate; diethyleneglycoldinitrate; trimetrioltrinitrate; triacetin; diethylphthalate; etc. The aforementioned materials are considered typical classes which can be utilized and the present invention is not considered to be limited thereto.

The staple utilized is a small piece of metal of very small dimensions which is added to the propellant batch specifically to improve performance. The staple may be of any configuration, e.g., rectangular or cylindrical. The substance of the staple may be a magnetizable material, notably a highly magnetizable metal such as iron, cobalt or nickel, or combination thereof with a non magnetizable metal, e. g. copper, silver, gold, aluminum, zirconium, tungsten, etc., including alloys thereof. The staple may be composite in construction which may be achieved through rolling, stamping, gluing, welding, brazing, twisting, knotting, etc. The more effective arrangements are small rectangular shapes of metals or combinations of metals. The metallic staple may also be combined with a coating, casing, etc. of a non-metallic material, e.g. an organic polymer such as polyethylene, nylon, etc. The invention is not considered to be limited by the above choices, as others would be suggested to a person skilled in the art.

It is an object of this invention to provide and disclose a solid propellant composition having improved performance characteristics.

It is a further object of the invention to provide and disclose a solid propellant composition having magnetically oriented staples incorporated therein.

It is a further object of this invention to provide and disclose a method for magnetically orienting staples in a solid rocket propellant.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawing in which:

FIG. I is a process flow sheet of the present method.

FIG. 2 is a schematic of a system for the radial orientation of staples in a solid propellant prior to magnetical orientation.

FIG. 3 is a view through line 33 of FIG. 2.

FIG. 4 is a schematic of a system for the radial orientation of staples in a solid propellant after magnetical orientation.

FIG. 5 is a view through line 55 of FIG. 4.

FIG. 6 is a schematic of an alternative system for the parallel orientation of staples in a solid propellant prior to magnetical orientation.

FIG. 7 is a schematic of an alternative system for the parallel orientation of staples in a solid propellant subsequent to magnetical orientation.

FIG. 8 is a graph comparing the burning rate performance of a propellant composition with a radial oriented aluminum clad steel staple incorporated therein with a base composition.

Set forth below are examples of the method utilized to carry out the present invention.

EXAMPLE 1 A 3,000 gram batch was prepared of a composition consisting of the following components in the percent by weight indicated:

a. 21 percent of a powder consisting of 90.0 percent nitrocellulose (12.6 nitrogen); 8.0 nitroglycerin and 2.0 percent nitrodiphenylamine, having a diameter of approximately l0 microns,

b. 0.5 percent of a powder consisting of 75.0 percent nitrocellulose (12.6 percent nitrogen); 24.0 percent nitroglycerin, and 1.0 percent 2- nitrodiphenylarnine, having a diameter of approximately 20-30 microns,

c. 44.5 percent of a solvent consisting of 34.0 percent butanetrioltrinitrate; 65.0 percent triethyleneglycol-dinitrate, and 1.0 percent 2- nitrodiphenylamine,

d. 13.0 percent aluminum comprising an atomized powder of approximately 15 microns in diameter,

e. 21.0 percent ammonium perchlorate atomized powder approximately 10 microns in diameter, and

f. 2.0 percent resorcinol, reagent grade.

The ingredients were positioned in a vertically agitated jacketed vessel of approximately 2 gallon capacity. The jacket of the vessel was connected to a circulating hot water source. The batch was agitated at a temperature of to F at approximately 30 rpm under a vacuum of approximately 10mm of mercury. Agitation was continued until all ingredients were wetted and a batch viscosity of approximately 30,000 centipoises was achieved. This mixing covered a period of approximately 1 to 2 hours. After the desired viscosity was achieved 30 grams (1 percent by weight) of a staple was added to the batch. The staple utilized was composed of an inner layer of steel foil of approximately 0.0042 inch thickness to which was bonded by rolling two outer layers of aluminum foil each of approximately 0.0004 inch thickness. The layered foil was then cut to give staple pieces each approximately 0.005 inch in overall thickness, 0.015 inch wide and 0.170 inch long. The staple containing composition was agitated under mm l-lg at 30 rpm at a temperature of 90 to 100F for a period of approximately minutes.

Thin walled cellulose acetate cylinder 11, which was closed at the bottom by removable plug 13, was utilized to cast the propellant. Illustrative, but without limitations, the casting cylinder utilized had an inside diameter of 3.29 inches and a height of 4.0 inches. While a cellulose acetate form was utilized, other materials, e.g., steel are operable. Cylindrical rod 15 constructed of carbon steel was inserted in a depression in plug 13, not shown, in a position coaxially with cylindrical form 11. The rod was approximately 1.29 inches in diameter. Rod 15 extends approximately 8 inches beyond the open end of form 11. Coil l7 composed of 1,908 turns of a 15 gauge copper magnet was affixed to the upper end of rod 15. The coil in turn was connected to a 12 volt battery source, designated 19. The current was adjusted and controlled by potentiometer 21 and switch 23.

In operation, form 11 is filled with a composition containing staples 25. Switch 23 is closed as shown in FIG. 4 to complete the electrical circuit between battery l9 and coil 17 positioned on rod 15 thereby radially orienting staples 25 in the propellant composition, as illustrated in FIG. 5. Current through the coil was adjusted to 1.0 ampere. Cellulose acetate form 11 and the magnetic apparatus, excluding the battery, were then placed in an oven maintained at a temperature of l40F in order to solidify the mixture. The mixture was left in the oven for a period of 3 days. The current to the coil was discontinued after a period of one day and the coil removed when it was considered that the mixture was sufficiently solid so as not to affect the staple orientation due to settling. Propellant grains prepared by the above process were statically fired in rocket motors for measurement of pressure-time characteristics. A base composition identical to the present composition but containing no metal staples was prepared and also statically fired in rocket motors for measurement of pressure-time characteristics. The data obtained was used to calculate burning rate-pressure performance, as illustrated in FIG. 8. The data obtained indicates that improved performance, i.e., a burning rate increase of about 40 percent, was obtained through the employment of the present magnetically oriented staple containing composition. The pressure-time characteristics obtained with the magnetically oriented staple containing composition were very uniform, smooth and reproducible. In contrast thereto the pressure-time characteristics obtained with the identical staple containing composition, wherein the staples were not magnetically oriented, tended to be non-uniform, irregular and nonreproducible. By alignment of staples according to this invention it was possible to approach maximum buming rates achieved with continuous wire filaments.

EXAMPLE 2 The method of Example l was modified to include 1.5 percent lead chromate by weight as a performance additive in the base composition of Example 1, and 1.0 percent by weight of a silver clad nickel foil 0.001 inch thickness cut to approximately 0.005 by 0.125 inch was added as the staple in place of the aluminum clad steel staple. An identical composition but containing no staples was also prepared. The propellants prepared with and without the radially oriented staples were test fired at ambient temperatures in static rocket motors. A to 200 percent increase in burning rate at 1,000 psi pressure was obtained by the utilization of the present propellant. In addition to the improved burning rate performance, pressure-time histories of combustion were extremely uniform and smooth.

EXAMPLE 3 A 3,000 gram batch was prepared of a composition consisting of the following components in the percent by weight indicated:

a. 55 percent of a powder consisting of 90.0 percent nitrocellulose (12.6 nitrogen), 8.0 percent nitroglycerin, 2.0 percent Z-nitrodiphenylamine, approximately 10 microns in diameter, and

b. 45 percent of a casting solvent consisting of 34.0

percent butanetrioltrinitrate, 65.0 percent triethyleneglycoldinitrate and 1.0 percent 2- nitrodiphenylamine. All other aspects of the invention practiced in this example were identical to those utilized in Example 1. An identical composition was prepared except that no staples were incorporated. The propellant grains prepared with and without the radially oriented staples were tested in rocket motors. Grains prepared in accordance with the present invention exhibited increased buming rate performance concurrent with smooth and uniform pressure-time combustion histories.

EXAMPLE 4 A propellant composition was prepared in accordance with the procedure set forth in Example 1. Alternative means of magnetically orienting the staples were utilized as shown schematically in FlGS. 6 and 7. The drawings illustrate that the apparatus for magnetization may be designed to any desired type of predetermined form to achieve orientation of the staple within the mixture to specific directions.

Although we have described our invention with a certain degree of particularity, we wish it to be understood that we do not desire to be limited to the exact details of formulations of propellants and means of magnetization shown and described, for obvious modifications will occur to a person skilled in the art.

Having described our invention, we claim.

1. A solid propellant composition having a dispersed staple, magnetically oriented therein said staple being a composite of a magnetizable metal, said magnetizable metal being nickel, and of another metal joined thereto, said other metal being silver.

2. A solid propellant composition in accordance with claim 1 wherein the staple is radially oriented.

3. A solid propellant composition in accordance with claim 1 wherein the staple is parallel oriented.

4. A solid propellant composition in accordance with plaim 1 wherein the metal staple is a silver clad nickel oil. 

2. A solid propellant composition in accordance with claim 1 wherein the staple is radially oriented.
 3. A solid propellant composition in accordance with claim 1 wherein the staple is parallel oriented.
 4. A solid propellant composition in accordance with claim 1 wherein the metal staple is a silver clad nickel foil. 